Polymeric materials have been widely used for years in both medical and dental applications. Such applications include surgical and body implants and other prosthetic devices, (e.g., heart valves, blood vessels, etc.). In dentistry, for example, polymer materials have been used to produce removable dentures, temporary crown and bridge materials, restorative materials, impression materials, and the like.
It is generally desirable that medical implants be radiographically opaque such that their precise location within the host body can be detected by X-ray examination. In addition, it is advantageous that such medical implant be optically or visually transparent so that a flow of fluid therethrough may be observed. Therefore, a vast amount of prior art has been directed at the preparation of polymeric materials for use in medical or dental applications that can be detected by X-ray analysis.
In the field, however, of animal chew toys, it is certainly the case that a variety of disclosures exist detailing specific resins and specific designs to enhance the attractiveness of the chew toy to an animal. In addition, numerous disclosures exist that attest to the use of specific materials, and specific additives, and specific molding conditions for a chew toy product.
Along such lines, attention is directed to U.S. Pat. No. 3,871,334 to Axelrod, which discloses a chewable object from nylon with a flavor or odor extract. Attention is also directed to U.S. Pat. No. 4,513,014 which sought to provide a more chewable product comprising a polyurethane elastomer again having incorporated therein a flavor or odor extract.
Attention is next directed to Applicant's U.S. Pat. No. 5,827,565 which discloses a process for making a heat expandable dog chew comprised primarily of injection molding potato starch granules and an attractant. Attractants recited include chicken powder, liver powder, ham, turkey, beef and or fish. Vegetable additives such as spinach or carrots also may be added. The resultant mixture is molded under heat and pressure into a desired form, such as a dog bone. The dog bone so produced can be modified in texture or hardness by subsequent heating, preferably in a microwave oven.
In Applicant's U.S. patent application Ser. No. 09/138,804, which was a continuation-in-part of U.S. Pat. No. 5,827,565, there is disclosed a dog chew having natural fruit flavor to increase the dog's appetite for such chew. Such fruit flavored dog chew may also include natural food coloring to enhance the attractiveness of the chew to the dog owner. The food coloring may also correspond to the fruit flavor, and the dog chew disclosed therein may also embody a breath sweetener for a dog such as mint, spearmint, peppermint or wintergreen and may also include parsley. The preferred form of such edible chew maintained the basic ingredient of a heat-expandable starch, such as potato starch. Fruit flavoring may be added to the granules of a mixture of potato starch, water and calcium carbonate along with natural fruit flavorings.
Attention is also directed to the following U.S. Patents and copending applications, commonly owned by the assignee herein: U.S. patent application Ser. No. 08/310,575 filed Sep. 22, 1994 entitled “Molded Rawhide Chew Toy”, now U.S. Pat. No. 5,476,069; Ser. No. 08/923,070 filed Sep. 3, 1997 entitled “Vegetable Based Dog Chew”, now U.S. Pat. No. 6,093,427; Ser. No. 08/738,423 filed Oct. 25, 1997 entitled “Edible Dog Chew”, now U.S. Pat. No. 5,827,565; Ser. No. 08/784,834 filed Jan. 17, 1997 entitled “Carrot-Based Dog Chew”, now U.S. Pat. No. 5,941,197; Ser. No. 08/888,611 filed Jul. 7, 1997 entitled “Vegetable Dog Chew”, abandoned; Ser. No. 09/114,872 filed Jul. 14, 1998 entitled “Heat Modifiable Edible Dog Chew”, now U.S. Pat. No. 6,180,161; Ser. No. 09/138,804 filed Aug. 21, 1998 entitled “Improved Edible Dog Chew”, now U.S. Pat. No. 6,126,978; ser. No. 09/116,070 filed Jul. 15, 1998 entitled “Wheat & Casein Dow Chew With Modifiable Texture”, now U.S. Pat. No. 6,110,521; Ser. No. 09/116,555 filed Jul. 15, 1998 entitled “Heat Modifiable Peanut Dog Chew”, now U.S. Pat. No. 6,093,441; Ser. No. 09/227,767 filed Jan. 8, 1999 entitled “Method of Molding Edible Starch”, now U.S. Pat. No. 6,159,516. In addition to such patents and applications, attention is also directed to the art cited in said patents and applications, as such art relates to the field of molded starch products.
As can therefore be seen upon review of all the above, a number of disclosures exist which point to the importance of the use of radiopaque polymer systems for humans. Such disclosures are directed at monitoring the location of an implant via X-ray analysis. In addition, a variety of disclosures exist directed an animal chew products.
However, to date, animal chew toys have been made without consideration of X-ray analysis issues, or in effect, chew toys have been made such that they are inherently transparent to X-ray detection, and as such, are not detectable within the animal if such chew toy should be improperly ingested. Accordingly, there has existed a long-standing need to develop and provide an economical process to produce an animal chew toy so that the chew toy can be detected by standard X-ray analysis by trained medical professionals.
In addition, although incidents of ingestion of oversized “chewed-off” sections of plastics are relatively rare compared with other foreign objects ingested by the animal, the occurrence may nonetheless result in a severe medical emergency or even death. The potential severity of such an incident makes it important to facilitate the diagnosis and removal of such foreign bodies, regardless of the fact that such event remains outside normal and reasonable expectations.
What is needed therefore is a material or material combination that can maximize the radiopacity of an animal chew without negatively affecting the physical characteristics of the animal chew. Such chew toy should also remain safe for ingestion and must also preserve the associated chewing experience for the animal.
Therefore, it is one object of this invention to produce an animal chew toy that remains attractive to the animal, providing a healthy and engaging chewing experience, but which if improperly ingested can be detected by X-rays and more rapidly removed from the animal in any life-threatening situation.
More specifically, it is also an object of the present invention to establish critical, safe and effective concentrations of a radiopaque additive in a host polymer resin to provide X-ray detection when present in a sized portion of the chew, such sized portion typical of a “break-off” piece of the chew due to animal chewing action.